Unanswered question

We are running 6+hr Soak test using one controller and 6 Load generator machines with 250 Vusers.We are getting “More memory is required to compute the statistics... “ error (please refer to snapshot) while the neoload trying to generate the final summary page.The controller machine has 4GB RAM.Please let us know what is the configuration change that is required to avoid this? Also What is the optimal setting for results to ensure only the required information is generated for a long running test? Please clarify.